These air filters are superior in quality and function, I even use the highest filtration level as a top notch replacement for hepa filtration in appliances and air filters at my business for decades now. One will easily be able to discern the difference in air quality when in use in just a few minutes. One can even make an inexpensive quality air cleaner with an ordinary household fan and and air filter simply taped to it as is demonstrated by a Professor at the University of Michigan on you tube. Really a need for most homes in all American cities today.